Compressor



A 1934- s. R. HIRSCH 1,969,076

. I COMPRESSOR I Filed March 22, 1934 5 Sheets-Sheet 1 STAGE CUM/"[[SSOEPffJ'J'l/kt' FLUID 43 comma:

arm/we N 611?. Hirsch INVENTOR B y M A TTORNEY 3 Sheets-Sheet 2 s. R.HIRSCH COMPRESSOR Filed March 22, 1934 Aug. 7, 1934.

SKJYim'ch INVENT OR A ORNEY I Aug. 7,: 1934. s R scH I 1,969,076

COMPRESSOR Filed Mar ch 22, 1934 s Sheets-Sheet 3 N G? a. Y

INVENTOR BY TTORN Patented Aug. 7, I934 Uhii'i'h S'E'TES Worthingto nPump and Machinery @orpora tion, New York, N. 31C, a comration off Wirgiaia application March 22,

This invention relates to compressors for air or gas and an object oi.the invention isto provide a compressor unloading means and controltherefor, whereby an approximate constant or predetermined weight. ofgas will be delivered at varying suction pressures and at a constantdischarge pressure with a reciprocating compressor operating at constantspeed.

More specifically the invention comprises a multi-stage compressor, andloading and unloading means therefor, which unloading means iscontrolled by pressure of gas entering the suction or inlet of thecompressor whereby the capacity oi the compressor stages is controlledin steps proportionate to the suction pressure, for maintainingapproximately constant the weight and pressure of gas delivered by thecompressor.

With these and other objects in view as may appear from the accompanyingspecification, the invention consists of various features ofconstruction and combination of parts, which will be first described inconnection with the accompanying drawings, showing a compressor of thepreferred. form, and the features forming the invention wili bespecifically pointed out in the claims.

In the drawings:

Fig. 1 is a diagrammatic view or a system view showing a multi-stagecompressor and control mechanism therefor for carrying' out the objectoi the present invention.

Fig. 2 is a diagrtic view partly in sec-= tion of a modified form oi thecompressor layout.

Fig. 3 is a diagrammatic view partly in section of a still furthermodified form or the invention.

Referring more particularly to the drawings, Fig. 1 shows one approvedtype of compressor layout and control whereby a multi-stage variablecapacity compressor may be operated to deliver an approximate constantor predetermined weight of gas at various suction pressures and at aconstant discharge pressure with a reciprocating compressor operating ata con stant speed. v

The layout shown in Fig. 1 is particularly adapted for treating crudepetroleum oils and specifically Ior use in what is lmown as the propanepump-down dewaxing system. While the compressors and their control areshown as applied in Fig. 1, to a petroleum dewaxing system, it is to beunderstood that the invention is not to be limited to such systems butis applicable u-ior use in any analogous system or in any systern whereit is desired to carry out the broad specific idea of delivering a gasat a constant or predetermined weight and constant discharge pressurewith varying intake pressure without varying the speed or operation orthe compressor. so

in the system shown in Fig. i of the drawings, the petroleum to mdewaxed is mixed with propane or the like and is placed in a storagetank 1 "from which the gas is drawn ofi through the pipe 2 to thesuction of the first stage or low so pressure cylinder 3 of themulti-stage reciprocating compressor. The gases are discharged from thedischarge, indicated at a, of the first stage compressor 3 to thesuction of the second stage or high pressure cylinder 5 of thecompressor. go From the high pressure cylinder 5 the compressed gasesare discharge through. a suitable conduit 6 to a condenser 7 where theyare con densed and the propane separated or scarc gated from the othergases for future use in X5 connection with other petroleum.

In the process for dewaxing lubricating stock, propane is blended withadefinite amount of lubricating stock and held in a closed tanlr, thepressure of which is fixed by the temperature so and vapor pressure ofthe volatile constituent, namely, propane. Separation is accomplished byprogressively decreasing the pressure in the closed tank, under whichcondition the propane is evaporated and the amount of separation is as.proportional to the latent heat of the propane which is evaporated andremoved. As the propane is removed, the pressure and consequently thetemperature in the tank drops resulting in 'a'congealing or the parafllnor wax base of the 9d mixture, which congealing wax falls to the bot--tom of the tank and is segregated.

In order to control the rate of separation, it is necessary to controlthe rate at which the propane is evaporated and removed. During the DE.initial stages of the process the pressure within the tank is relativelyhigh, and therefore the volume of vapors to be removed to accomplish agiven amount of separation is relatively small as compared with thevolume which must be removed at the later stages of the process when thepressures are low and the specific volume of the gas removed is large.

At the beginning of the process the compressor is required to remove gaswhich is relatively dense, so that to remove a definite weight of gasthe volume to 'be removed is small. As the pressure within the tankdecreases the gas becomes less dense, and therefore the volumecorresponding to a. given weight of gas increases,

so that the compressor must work at an increasing volumetric capacity asthe process progresses. It must be remembered that at the beginning ofthe process the ratio of compressions is small and from this point theratio of Y compressions gradually increases until at the end of theprocess the ratio is relatively large.

It will be appreciated that the ratio of pumping of the gas from thestorage tank must be definitely controlled so as to control the desiredrate of temperature change in the tank and consequently the rate atwhich the wax is congealed. The gas removed from the tank must bedischarged at a predetermined pressure maintained constant, into thecondenser 7. To provide these results a novel system of loading andunloading the compressor cylinders is provided which is controlled byany approved type of compressor unloading governor which governor is inturn pressure operated and controlled by pressure of the gasses enteringthe suction of the first or low pressure stage of the compressor.

In the construction shown in Fig. 1 oi the drawings, the first stage orlow pressure cylinder of the-compressor is of the approved type ofdouble acting compressor and is provided with suction valves 10 and 11which control the inlet of the gas into the opposite ends of thecylinder 12 and on opposite sides of the piston 13. 7 'These suctionvalves 10 are of. the unloading type such as disclosed in United StatesPatents Nos. 1,579,781 and 1,798,435 and* their specific constructionwill not be described in detail in the present application. The suctionvalves are of the unloading type and are held open by pressure so thatwhen the suction valve '10 is held open the crank end of the compressorcylinder 3 will operate without compressing, the

gas merely passing in and out through the suction valve. When thesuction valve 11 is held open the head end of the compressor cylinderwill operate without compressing, and when.

both suction valves are held open the compressor cylinder 3 will operateat zero'capa'city.

1 Clearance pockets 15 and 16 are shown which are adapted to beconnected to the ends'oi' the cylinder through the vmedium of pressureoperated'unloading valve structures 17 and 18 for the purpose ofIraotionally unloading the ends or the compressor. J

These pressure operated unloading valves 17 and 18 may be of anyapproved type such as those shown in Patent No. 1,764,646 wherein thevalves are opened when the pressure in the opcharges through a suitableconduit 22 into the suction 23 01' the second stage or high pressurecylinder 5 of the compressor.

- The second stage or high pressure cylinder '5 of the compressor isalso of the double acting l i'ractionally of the high pressure cylinder.When the presunloading the ends or the compressor independently or forcompletely unloading the compressor by having both of the suction valvesheld open. In the drawings only one clearance pocket, namely theclearance pocket 26, is shown associated with the high presssurecylinder 5 to provide fractional unloading thereof,-

but it is tobe understood that any desired number of clearance pocketsmay be provided without departing from the spirit of the presentinvention..

The various unloading valves and unloading suction .valves are operatedby pressure fluid which is delivered thereto through the distributingvalve structure 30 which forms a part of the governor mechanism 31.

The governor mechanism 31 is specifically illustrated and described inPatent No; 1,798,435. The distributing valve 30 is operated to controlthe-distribution of pressure to the various valves for loading orunloading of the compressor cylinders by the governor mechanism 31 andthe governor mechanism 31 is in turn controlled by the pressure operatedmechanism 32 which forms a part of the governor 31. The pressureoperated mechanism 32 is connected by means of the pipe 33 with thesuction of the low pressure cylinder 3 of the compressor. In thedrawings such connection is illustrated as being established through thepipes 33 and the delivery pipe 2 but the pipe 33 may be connecteddirectly to the suction of the compressor cylinder if desired.

By connecting the pressure operated mechanism-32 with the suction of thelow pressure compressor cylinder 3, the loading and unloading of thecylinders 3 and'5 will be controlled by the pressure of the gas enteringthe suction of the first stage or low pressure cylinder of thecompressor mechanism.

Thus; when the pressure gas in the storage tank 1 and consequently atthe suction of the low pressure cylinder 3 is high or atits greatestpoint the pressure operated mechanism 32 will through the mechanism 34of the governor 31 operate the distributing valve 30 to deliver pressurefluid through the pipes or connections 35 and 36 to: both of the suctionvalves 10 and 11 of the low pressure cylinder 3 for holding these valvesopen and permitting the gas from the tank 1 to pass through the lowpressure stage of the compressor without being compressed. It thepressure of the gas, is sumciently high then the valve 30 will. also atthe same time deliver pressure fluid through the distributing valve 30and pipes 3'1 and 38 to the suction valves 24 and 25 of the second stageor high pressure cylinder of, the compressor and thus the gas will passthrough both the compressor cylinders to the condenser without beingcompressed.

As the pressure falls in the storage tank and consequently as thepressure of the fluid at the suction of the low pressure cylinder fallsthe distributing valve 30 will be operated to close first the suctionvalve 25,'second the suction valve 24 at which time the high pressure.cyl-- inder' will be operated at full capacity. If the pressure or thesuction gas is slightly in excess of the desired pressure, the unloadingvalve39' which controls the clearance pocket 26 will be operated bypressure fluid from the distributingvalve30throughthepipe40soastopartlyor reduce the compressing capacitysure in the suction pipe 2 falls further, the unloading valve 39 will beclosed and the suction valve 11 of the low pressure cylinder will beclosed permitting the low pressure cylinder to operate at approximatelyfifty percent of capacity. iii the pressure of the suction gas is suchthat it is desirable to operate the low pressure cylinder at fiftypercent of capacity,- the clearance chamber 16 may be brought intocommunication with the head end of the cylinder 3 means of the unloadingvalve structure 18 which unloading valve structure will close when thesuction pressure falls to a suilicient predetermined demos to warrantoperation of first stage cylinder at fifty percent of capscity.

"Upon further drop in the pressure of the suc= tion the suction valvewill be closed which will permit the low pressure'cylinder to operate atone-hundred percent of its capacity. Should the suction pressure,however, be such. that it is not desirable to operate the low pressurestage at one-hundred percent capacity,-but only at seventy-five percentof capacity, the

clearance pocket will be brought into service by the opening of theunloading valve mechanism 17. The unloading valve 17 will close whenpressure of the gas at the suction of the low pressure cylinder falls tothe predetermined degree necessary for full capacity operation of thelow pressure stage.

The pressure fluid for operating the various suction valves 10, ll, 24!;and 25 and the unloading valves 17, 15 and 39 may be obtained from anysuitable source and it is delivered to the distributing valve throughsuitable piping indicated 42.

From the foregoing description taken in connection Fig. l of thedrawings, it will be apparent that with the layout of the compressor asshown and as above described the pressure or the suction gas at theinlet to the low pressure cylinder or first stage of the multi-stagecompressor will control the operation of the compressor and by so doingit will be possible branch 52 therein which passes to the suction of thesecond stage or high pressure cylinder 53 of the compressor-structure. Avalve chest 54 is interposed in. the pipe and a valve 55 is providedwhich controls the passage of the suction gas either through the suctionpipe so to the inlet of the cylinder 51 or to the inlet oi the pressurecylinder 53.

The valve 55 is shown in the drawings as a pressure operated valveoperated by pressure fluid distributed thereto through the distributorvalve 56. The distributor valve is the same as the distributor valve 30and the distributor valve ll of Patent No. 1,798,435. The distributorvalve 56 is operated by the governor mechanism 57 which is similar tothe governor mech-v anism 31 which governor inec is in turn controlledby pressure of gas passing through the suction. or intake pipe SDthroughthe mediu of the p essu e operated as.

When the pressure of the gas or air passing through the intake pipe 50is at a predetermined high degree the valve 55 will be operated tolay-pass the suction fluid past the low pressure cylinder 51 directly tothe high pressure cylinder 53 and when the pressure of the fluid in thepipe 50 falls to a predetermined degree the valve 55-will be operated todeliverthe suctiopi fluid to the suction of the low pressure cylinder51.

With the valve 55 interposed in the suction line to the first stage orlow pressure cylinder 51 it is unneceswy to provide unloading suctionvalves, and consequently any approved type of suction valve as indicatedat 60 may be provided for the first stage or lowpressure cylinder 51.Any number of clearance pockets such as the clearance pocket 51 may beprovided for permitting fractionalunloading of the low. pressurecylinder. Only one of such clearance pockets is shown in Fig. 2 of thedrawings but they are well known and various numbers and types ofclearance pockets are shown in prior patents, as for instance in PatentNo. 1,764,646. The clearance pockets may be opened to communication withthe cylinder by any approved type of unloading valves such as that shownat 62, and which. construction of pressure operated unloading valve isclearly shown and described in the last mentioned United States Patent.

The high pressure cylinder 53 is provided with unloading suction valves63 and 6d and with. a clearance pocket 55 to permit operation of thecompressor at fractional percentages of its capacity. The clearancemcket 65 is opened to the cylinder or out ofi therefrom by a pressureoperated unloading valve 65 which is of the same construction as theunloading valve 62.

While the specific construction of pressure operated valve is shown at55, it is to be understood that any approved type of either pressureoperated or manually operated valve may be substituted for theconstruction shown without departing from the spirit of the invention.In the operation of the modified construction shown in Fig. 2, when thepressure of the suction fluid passing through the pipe 50' is at apredetermined high pressure, for instance at its highest pressure, thegovernor mechanism 5'7 will operate the distributing valve 55 to in turnoperate the pressure valve 55 to by-pass the suction fluid past the lowpressure cylinder to the suction of the high pressure cylinder 53 and atthis time both the suction valves 63 and 64 will be held open permittingthe gas to pass straight through the compressor and out the dischargepipe 67. As the pressure of the suction fluid drops the suction valvescc and 63 will be successively closed through the operation of thegovernor mechanism 5'! to load the high pressure cylinder. If anintermediate capacity of the high pressure cylinder is desired than thegovernor mechanism may be regulated to open the clearance pocket 65, orany other desired out shown inFig. 2 will provide the same result asthat obtained from the structure illustrated in Fig. 1, diflering'fromFig. 1 principally in that the gas to be compressed is by-passed aroundor past the low pressure cylinder of the compressorinstead of beingby-passed through the low pressure cylinder as is the case in thestructure illustrated in Fig. 1.

In the layouts shown in Figs. 1 and 2 of the drawings, theloadingand-unloading of the compressor is controlled indirectly throughsuitable'pressure operated means by the pressure of the gas entering thesuction of the first stage of the compressor. However, it may at timesbe desirable to provide a construction in which a time factor will enterinto the control of the loading and unloading of the compressor topermitsuch operation irrespective of the pressure of the suction of gas.

.In Fig. 3 of the drawings such a layout is shown. In this modified formof layout, the compressor comprises the first or low stage compressor l5and the second or high stage compressor 76, which are constructed in anyapproved manner but are illustrated as being'constructed in the samemanner as the first and second stage compressors shown in Fig. 2 of thedrawings, their loading and unloading being controlled through themedium of the distribu'' torvalve '77 in the same manner in which thecompressor stages shown in Fig. 2 are loaded and unloaded. Thisconstruction shownin Fig.

' 3 also shows a pressure operated valve 78 for controlling the deliveryof the fluid to be compressed either to the first or second stagecompressor, being -,operableto permit the cutting out of the first stagecompressor to per-- nut the 888 to be by-passed directly" to the secondstage. However, it is to be understood that the time I controlledelement embodied in the governor mechanism and which forms the essenceof the modification shown in Fig. 3, may be used in connection with com-1presso'rs as'shown'in Fig. 1 of the drawings without departing from thespirit of the present invention. I

The distributor valve 7''! is operated by means of the governormechanism 79, which is the same in all essentials as governor mechanisms31'and 57, and is in turn operated by the pres- I sure operated meanswhich likewise is similar.

to the structures 32 and 58. However, this modifled constructionshown inFig. 3 differs from the structure shown inFigs. 1 and 2, in that thepressure fluid derived for operating the mech-' Ystartedrand operatingat a constantspeed of operation will operate the pump 82 for pump ingany suitable fluid into the reservoir 81. The steady constant speed ofoperation of the pump 82 will provide constant and even raising ofpressure in the reservoir 81, and this pressure fluid passing from thereservoir 81 through the pipe 84 to the pressure operated'means 80 willoperate the governor 79' which will in turn operate the distributingvalve 77 and control the loading and unloading of the compressor. Thetime factor enters into the various stepped loading of the compressor,in that the pressure in the tank .81 is built up in a predeterminedsteady flow and by regulating the governor'79 for operation at definitepressures, the loading of the compressor will be controlled at definitetime intervals predetermined upon the intervals between such definitepressures being provided in the reservoir 81. It will be understood thatthe invention is not to be limited to the specific construction orarrangement of parts shown but that they may be widely modified withinthe invention defined by the claims.

I What is claimed is: a

1. The combination with a compressor ofcontrolling means for loading andunloading the compressor'in successive steps of predeterminedpercentages of cylinder capacity, pressure operated means for operatingsaid controlling means, said pressure operated means connected to thecompressor suction whereby the loading and unloading of the compressorwill be controlled by pressure of inlet gas thereto.

2. The combination with a multi-stage compressor, of controlling meansfor loading and unloading the compressor in successive steps ofpredetermined percentages of cylinder capacity, pressure operated meansfor operating said controlling" means, said pressure operated meansconnected tothe suction of said compressor whereby the loading and ofthe compressor will. be varied in proportion to the variations in thepressure of inlet gas to the compressor.

' 3. The combination with a multi-stage com- .pressor, of means forby-passing gas to be com-' pressed past the low pressure stage of thecompressor, pressure operated means controlling operation'of said firstnamed means, said pressure operated means connected to the suction ofthe compressor for operationby pressure of inlet gas to theco'mpressor.I

4. The combination with a multi-stage compressor, .of means for by-passing gas to be compressed post-the low pressure stage ofthe'compressor, controlling-means for loading and unloading thecompressor in successive steps 'of predetermined percentages of cylindercapacity, pressure operated means for controlling opera tion of saidfirst named means and said unloading controlling means, said pressureoperated'means connected to the suction of the high pressure stage, ofmeans for rendering the low pressure stage of the compressornon-compressing, unloading'means for unloading the high pressure stageof the compressor in succes sive steps ct predetermined percentages ofcylinder capacity, pressure operated means controlling operation of saidfirst named means and or said unloading means, said pressure operatedmeans connected to the suction of the compressor for operation bypressure 01' inlet gas to the compressor.

6. The combination with a compressor, of controlling means for loadingand unloading the compressor in successive steps of predeterminedpercentages of cylinder capacity, said controlling means including meansfor holding open the suction valves of the comprcsson'pressure operatedmeans for operating said un1oad-. ing means, said pressure operatedmeans connected to the compressor suction, whereby the loading andunloading of the compressor will be controlled by pressure of inlet gasthereto.

7. The combination with a muiti-stage compressor, or controlling meansfor loading and unloading the compressor in successive steps ofpredetermined percentages of cylinder capacity, said controlling meansincluding means for holding open the suction valves of the compressor,pressure operated means for operating said controlling means, saidpressure operated means connected to the suction of said coinpressorwhereby the loading and unloading of the compressor will be regulated inproportion to variations in the pressure of inlet gas to the compressor.

3. The combination with a rnulti-stage corn= pressor including a highpressure stage and a low pressure stage, of controlling means forloading and unloading the compressor in successive steps ofpredetermined percentages o2 cylinder capacity, said controlling meansincluding means for holding open the suction valves of the low pressurestage of the com pressor whereby gas to be compressed will be Icy-passedthrough the low pressure stage of the compressor, pressure ope-ratedmeans for operating said controlling means, said pressure uperated meansconnected to the suction of said the low pressure cylindernon-compressing,

means for rendering the high pressure cylinder non-compressing, andselective means controlled by pressure of gas at the suction of the lowpressure cylinder for operating said controlling means and for operatingsaid means for rendering the cylinders non-compressing.

10.111 a compressor for delivering an approximate constant weight of gasat varying suction pressures and at a constant discharge pressure with aconstant speed of operation of the compressor, in combination, with amultistage compressor including a low pressure cyl-' inder and a highpressure cylinder, of controlling means for loading and unloading thecompressor in successive steps of predetermined percentages of cylindercapacity, means for rendering the low pressure cylinder non-compressing,means for rendering the high pressure cylinder non-compressing, meansoperated by pressure of gas at the suction-of the low pressure cylinderR c-w for operating said controlling means and for operating said meansof rendering the cylinders non-compressing.

11. The combination with a compressor, of controlling means for loadingand unloading the compressor in successive steps of predeterminedpercentages of cylinder capacity, and selective means controlled bypressure of gas at the suction of the low pressure cylinder foroperating said controlling means.

12. The combination with a multi-stage compressor including a highpressure stage and a low pressure stage, of means for lay-passing gas tobe compressed past the low pressure stage of the compressor, andselective means controlled by pressure of gas at the suction of the lowpressure stage for operating said first named means.

13. In a compressor for delivering an approximate constant weight of gasat varying suction pressures and at a constant discharge pressure'with aconstant speed of operation of the compressor, in combination, with amultistage compressor including a low pressure cylinder and a highpressure cylinder, an intake 1% pipe connected to the suctions of saidcylinders and. a valve in said pipe iorcontrolling the deliveryto saidcylinders of the fluid to be compressed.

14. In a compressor for delivering an approxim5 mate predeterminedWeight of gas at varying suction pressures and at a constant speed ofoperation of the compressor, in. combination, with a multi-stagecompressor including a low pressure cylinder and a high pressurecylinder, 3110 an intake pipe connection to the suction of saidcylinders, a valve in said pipe for controlling the delivery to saidcylinders of thafluid to be compressed, and means for operating saidvalve, said means connected to said intake pipe, whereby pressure offluid flowing through the pipe will control operation of the valve,

15. In a compressor for delivering an approximate predetermined weightoi gas at varying suction pressure, and at a constant discharge 1%pressure with a constant speed of operation of the compressor, incombination, with a multistage compresscr including a low pressurecylinder and a. high pressure cylinder, an intake pipe connected to thesuctions of said cylinders, 325 a valve in said pipe for controlling thedelivery to said cylinders of the fluid to be compressed controllingmeans for loading and unloading the compressor in successive steps ofpredetermined percentages of cylinder capacity, and means for 13poperating said valve and said controlling means, said means connected tosaid. pipe whereby pressure of fluid flowing through the pipe willcontrol operation of said controlling means and said valve. 13g

16. In a compressor for delivering an approximate predetermined weightof gas at varying suction pressures and at a constant discharge pressurewith a constant speed of operation of the compressor, in combination,with a multi- 1% stage compressor including a low pressure cylinderand-a high pressure cylinder, an intake pipe connected to the auctionsof said cylinders,

a valve in said pipe for controlling the delivery to the cylinders offluid to be compressed, control- 1% ling means associated with said highpressure cylinder for unloading and loading the high pressure cylinderin successive steps of predetermined percentages of cylinder capacity,means to: automatically operating said valve and for 166 lid 8 operatingsaid controlling means, said jmea'ns connected to said intake pipewhereby pressure of fluid flowing through the pipe will controloperation or said controlling means.

1'1. In a compressor for delivering an approximate predetermined weightof gas at varying suction pressures and at a constant discharge pressurewith a constant speed or operation of the compressor, in'combination,with a multistage compressor including a low pressure cylinder and ahigh pressure cylinder, of means for by-passing gas to 'be compressedpast the low pressure stage oi'the compressor, and time controlledselective means for operating said first named means.

18. In a compressor for delivering an approximate predetermined weightof gas at varying,

suction pressures and at a constant discharge pressure with a constantspeed or operation of the compressor, in combination, with a multi-,

stage compressor including a high pressure stage and a low pressurestage; of controlling means for loading and unloading said compressor insuccessive steps of predetermined percentages oi cylinder capacity, saidcontrolling means ininder and a high pressure cylinder, of controllingmeans for loading andunloading the compressor insuccessive steps ofpredetermined percentages of cylinder capacity, means for rendering thelow pressure cylinder non-compressing, means for rendering the highpressure cylinder non-compressing, and time controlled selective meansfor operating said controlling means and for operatingsaid means forrendering thecylinders non-compressing.

j SYLVAN R. mason.

- its its

